Magnetic latch mechanism



April 7, 1925. 1,532,212

G. o. WILMS MAGNETIC LATCH MECHANISM Filed April. 2'7, 1921 Gwsiav 0. 74111103 Patented Apr. 7, 1925.

umrao STATES 1,532,212 PATENT OFFICE.

GUSTAV O. WILLIS, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE RELIANCE GOM-PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

MAGNEI'IC LATCH MECHANISM.

Application filed April 27, 1921. Serial No. 465,084.

To all whom it may concern: I

Be it known that I, GUSTAV O. WILMS, a citizen of the United States, andresident of Milwaukee, in the county of Milwaukee and Stateof-Wisconsin, have invented new and useful Improvements in MagneticLatch Mechanism, of which the following is a description, referencebeing had to the which are a partaccompanying drawings, of thisspecification.

This invention relates to new and useful improvements in latchmechanisms and is more particularly directed to the provision of anelectro=magnetic latch mechanism for releasably securing a' switchmember in a,

closed position so long as the magnet is energized and for, uponde-energization of the magnet incidental to the occurrence of abnormalconditions in the system, causing the switch member to be opened,constitut ing what is commonl termed an under voltage release mechanlsm.

Such mechanisms have heretofore required a rather strong magnet coil andconsequently a comparatively large iron circuit, or in case of weakermagnet coils with a corresponding smaller iron circuit, a fine degree ofadjustment between the latch mechanism and the switch controlling memberheld thereby, to insure proper release of the switch member when the manetic pull is lowered to a predetermined limlt for o eration of thedevice. It is therefore an o ject of my invention to provide anarrangement in a latch mechanism of this character which makes practicalthe use of a comparatively small magnet but which eliminates thenecessity of an accurate machined adjustment of parts and which providesfor release of the'switch control membeliil at different degrees oflessened magnetic P The devices of the type described, as heretoforedesigned and constructed, have been unreliable, in that the latch partstend to freeze or adhere together when the switch has been closed for anperiod of time. As a result of which the atch mechanism fails to releaseupon the magnetic pull being lower to the degree necessary for theoperation of the device.

Hence, it is another object of this invention to increasethe certaintyof operation of a latch mechanism of this character by providing meansfor imparting a hammerlike blow to the latch element proper when thereleasing member is actuated.

This invention has for a further object to provide -a latch element forreleasably securing a holding member in one position and having aconnection with an armature, which connection includes a spring adaptedto be under compression when the armature is held in engagement with thecore of its magnet coil, whereby, upon a release of the armature byde-energization of the magnet, the energy stored in said spring willimpart a quick outward movement to the armature causing the same to givethe latch element a sharp hammer-like blow to insure the release of thelatch mechanism in the event the parts thereof have become frozentogether.

A still further object resides in the provision of a latch mechanismembodying the foregoing advantages which is of exceedingly simple andcompact structure.

With the above and other objects in View which will appear as thedescription proceeds, my invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaims.

In the accompanying drawing, I have illustrated one complete example ofthe physical embodiment of my invention constructed according to thebest mode I have so far devised for the practical application of theprinciples thereof, and in which:.

Figure 1 is an clevational View of a magnetic latch mechanism embodyingmy invention, and

Figure 2 is a side view of the latch mechanism, with portions thereofbroken away to more clearly disclose the structure.

Referring now more particularly to the accompanying drawings, 5designates a support wall on which is secured the base-plate .6 of apreferred embodiment of my improved latch mechanism. An electro-magnet 7is secured on one end portion of the base-plate and a bearing-bracket 8projects from the other end portion of the baseplate in which isjournaled one end portion of a switch shaft 9 operable upon rockingmovement to control the switch members nism, said arm carrying a rollerpintle 11 at its end. A spring 12 is mounted on said shaft for urging itin one direction, and this spring is merely intended to exemplify anymedium for urging the shaft from its latchheld position. A pair of arms13 project from the baselate between the magnet and the shaft an carry apivot-pin 14. An armature 15 is provided for the magnet 7 and'has a pairof arms 16 extended there-' from and pivotedron the pin 14 and thendirected inwardly, said arms forming continuations of certain of thelaminations of which the armature member is composed.

The latch element proper is mounted on the pivot-pin between thearmature arms 16 and comprises a hook-bar 17 adapted to receive theroller pintle 11 within its outer hook portion. The inner end portion ofthe bar is given a quarter twist and carries a bolt 18 which projectsbetween the inner ends of the armature arms and carries an expansilecoiled spring 19 having its ends engaged in cups 20 which bearrespectively against the ends of the armature arms and against aretaining nut 21 threaded on the stress on the holding outer end portionof the shaft, a lock-nut 22 being also threaded on the outer end portionof the shaft to maintain the nut 21 in properly adjusted position. Thebill portion of the latch hook presents a cam surface to the rollerpintle 11 of the holding arm 10 whereby the tendency to outward movementof the holding arm and intle is translated into a rocking stress on t elatch element whereby to rocure the disengagement of the pintle f i'omthe latch element upon the release .of magnetic tension.

Taking up now the operation and advantages of the before describedmechanism, it will be observed that, when the ma et 7 is energized andholding armature 15 thereagainst, as shown in Fi 2, the outward pint e11 will rock the latch element 17 an impart compression to the spring19.- Hence, when the magnet 7 is de-energized, or its energy reduced vtoa predetermined limit, the tension of the spring 19 will impart apositive rocking movement to the armature tending to break the action ofmagnetism which may linger in the core of the electro-magnet, and thearmature in this swingingmovement under the influence of the spring willimpart a hammer blow to the inner end portion of the latchelement-through the arms 16, utilizing the momentum thus acquired in thearmature member to impart a positive rocking movement to the latchelement and thus "magnet 7 insure its disengagement from the holdingmember constituted by the roller pintle 11.

It will be further notedthat the pressure of the holding pintle 11against the cam surface of the bill of the latch element may exert areleasing force which is rather slow in action and in initial actuationof the latch mechanism, this action of the holding pintle 11 may beexerted over an appreciable period of time to store energy in the spring19, which energy is instantly available to procure a maximum eflort ofdisengagement upon release of the detent means for the latch element,constituted in the present instance by the armature 15 and It will bealso noted that pivotal movement of the latch element varies the angleof its holding cam face opposed to the holding pintle 11 and thus variesthe tension exerted through the latch mechanism by the spring 12 orother medium for procuring dlsengagement. Hence, by adjusting the nuts21 and 22, the holding angularity of the latch element may be adjustedto thus adjust the tension exerted through the latch mechanism andconsequently adjust the releasing action of the latch mechanism for apredetermined lessened degree of energization of the magnet 7 in theevent that it would be desired to release the latch mechanism prior tosubstantially complete deenergization of the magnet.

From the foregoing description taken in connection with the accompanyingdrawing, it will be'readily obvious to those skilled in the art to whichan invention of this char-- acter appertains, that any adhering orfreezing together of the parts is overcome by the hammer blow impartedto the latch element proper upon the magnetic pull on the armature beinglowered to the predetermined degree, thus insuring the positive releaseof the latch mechanism.

What I claim as my invention is:

1. In a device of the class described, the

combination of a holding member, a latch element engageable with theholding member, a magnet which exerts force to hold the latch element inengagement with the holding member, and a yieldable means for impartinga hammer blow to the latch element when the force exerted by the magnetreduces to a predetermined value.

2. In a device of the class described, the

combination of a holding member, a latch element engageable with theholding member, a magnet which exerts force to hold the latch element inengagement with the holding member, an armature for the magnet, and aconnection between the latch element and armature, whereby the armatureimparts a hammer blow to the latch element when the force exerted by themagnet reduces to a predetermined value.

3. In a device of the class ,described, a holding member, a. latchelement engageable with said holding member to releasably secure thesame in one position, a movable member, means releasably securing themovable member in a locking position, and a connection between saidlatch element and movable member for retaining the latch element inengagement with the holding member when the movable member is in lockingposition and for imparting a hammer blow to the latch element when themovable member is released by its securing means, whereby thedisengagement of the latch element from the holding member is insured.

4. In a device of the class described, a holding member, a latch elementengageable with said holding member to releasably secure the same in oneposition, a movable member, means releasably securing the movable memberin a locking position, and a spring connection between the latch elementand movable member and adapted to be under compression when the movablemember is in looking position to retain the latch element in engagementwith the holding member, the energy of said spring connection beingreleased upon a release of said movable member by its securing means toimpart a hammer blow to the latch element and insure its disengagementfrom the holding member.

5. In a device of the class described, a holding member, a latch elementengageable with said holding member to releasably secure the same in oneposition, a movable member, means releasably securing the movable memberin a locking position, a pro jection carried by said latch element, anarm carried by said movable member and aris released and the arm of themovable member engaging the latch element projection to disengage theelement from the holding member.

6. In a device of the class described, a holding member, a latch elementengageable with said holding member to releasably secure the same in oneposition, a movable member, means releasably securing the movable memberin a locking position, a projection carried by said latch element, anarm carried by said movable member and arranged in the path of saidlatch element proj ection, and a connection between latch memberprojection and movable member arm including a spring adapted to be undercompression to hold the latch element in engagement with the holdingmember when the movable member is retained in its locking position byits securing means, said spring moving the movable member from itslocking position when said securing means is released and said movablemember moving under action of said spring for a short distance when itsarm engages the projection of the latch element to impart a hammer blowthereto and insure its disengagement from the hold ing member.

In testimony whereof, I afiix my signature.

GUSTAV O. W'ILMS.

